We plan to synthesize ring-substituted derivatives of cyclophosphamide which are isomeric at phosphorus in order to test the biological effect of reversing the axial-equatorial relationship of the mustard moiety and the phosphoryl oxygen. Studies are also continuing in our efforts to resolve the enantiomers of cyclophosphamide to determine which (if either) optical antipode is biologically more active. Further development of syntheses of neutral phosphorus-ester derivatives of cAMP and platinum complexes of cyclophosphamide derivatives will also be carried out.